Thank you for posting. Could I see a few pictures of this operator removed from the window? That will help us identify what you need. Can you also tell me the distance between its screw holes, center-to-center?
Screw hole, center to center is the same as bolt head, center to center. I measured it three times, since 840/1000 inch doesn't match any fractional size.
I rather not pull an operator out unless absolutely necessary, they are old, and, um, "cranky." Fragile.
May I suggest seeing what you have that matches the hole center dimension and see if anything pops up. I might be able to use non-awning, regular casement gear boxes if that's all that's available. I'm a good pseudo-engineer.